The Bible speaks of a seared conscience in 1 Timothy 4:2. The conscience is the God-given moral consciousness within each of us (Romans 2:15). If the conscience is “seared”—literally “cauterized”—then it has been rendered insensitive. Such a conscience does not work properly; it’s as if “spiritual scar tissue” has dulled the sense of right and wrong. Just as the hide of an animal scarred with a branding iron becomes numb to further pain, so the heart of an individual with a seared conscience is desensitized to moral pangs.

Paul identifies those who have a seared conscience in 1 Timothy 4:1–2: “The Spirit clearly says that in later times some will abandon the faith and follow deceiving spirits and things taught by demons. Such teachings come through hypocritical liars, whose consciences have been seared as with a hot iron.” In this passage, we learn three things about false teachers who lead others into apostasy: 1) they are mouthpieces for evil spirits, since they promulgate “things taught by demons”; 2) they are hypocritical liars, since they wear a mask of holiness but are full of falsehood; and 3) they are unscrupulous, since their consciences have been cauterized. This explains much. How can false teachers lie with no shame and spread deception with no compunction? Because they have seared consciences. They are past feeling that lying is wrong.

Earlier in the epistle, Paul speaks of the “good conscience” as opposed to the seared conscience. “Advancing God’s work,” he says, comes by faith, and love “comes from a pure heart and a good conscience and a sincere faith” (1 Timothy 1:4–5). A good conscience has the capability to tell right from wrong and is free from guilt. A person with a good conscience maintains his integrity. He enjoys fellowship with those who “walk in the light, as [Jesus] is in the light” (1 John 1:7). The lies of the devil are anathema to the one with a good conscience. Rather than follow the lies of apostates, he will “fight the battle well, holding on to faith and a good conscience” (1 Timothy 1:18–19).

Proverbs 6:27 asks a rhetorical question to illustrate the consequences of adultery: “Can a man scoop fire into his lap / without his clothes being burned?” To paraphrase the question in relation to false teaching, “Can an apostate dispense the fiery lies of hell without his conscience being seared?”